Cement for metallic and ceramic constructional parts



iOO. COMPOSITIONS, COATING OR PLASTIC.

asses Dec. 2,1935 7 2 3 9.

UNITED STATES PATENT OFFICE CEMENT FOR METALLIC AND CERAMICCONSTRUGTIONAL PARTS Artur Miihrle, Stuttgart, Germany, asslgnor toRobert Bosch Aktiengesellschaft, Stuttgart, Germany No Drawing.Application May 22, 1935, Serial No. 22,883. In Germany June 20, 1934 6Claims. (Cl. 106-30) The present invention relates to cements for 0.2-5%by weight of silicofluoride. The powdery joining constructional partsmade from metallic mixture of corundum powder and silicofluoride andceramic materials. is then mixed to a cement with concentrated wa- Themanufacture of many products or deter-lass sgmltion.

5 vices composed of many separate parts is often e consis ency of thecement is naturally de- 5 much simplified, if instead of a mechanicalfaspendent on the concentration and on the quantity tening together ofthe separate constructional of the water-glass solution added. parts, asufflciently firm and also otherwise suit- Experiments have now had thesuprlsing result,- able connection can be effected by cementing. thatthe concentration of the water-glass solu- 10 The object of theinvention is a cement for jointion can be decisive for the quality ofthe cement 10 lng constructional parts of metallic and ceramic forcertain purposes within the scope of applicamaterials, which possessesthe most varied possition stated. bilities of use in connection with.the group of It is therefore advisable to choose such a conmaterialsstated. This cement is equally suitable centration of the water-glasssolution to be added for joining metal to metal, and metal to ceramicthat will produce the quality of cement best suit- 15 material, as wellas for the Joining of ceramic ed for the particular purpose of use. Inthis way material to ceramic material. It consists of a one has atdisposal one of the two factors which mixture made with concentratedwater-glass so determine the consistency of thecement, the conlution offinely ground alumina, preferably cocentration of the water-glasssolution. By varyrundum powder, and silicofluorides, preferably ing thequantity of the water-glass solution added, 20

magnesium silicofluoride. the consistency of the cement can then beregu- It has been found by experience that one and lated according torequirements. the same cement is generally useful only for one Thus, forexample, when it is a question of the quite definite purpose. Thus, forinstance, the cementing of the central electrode of a sparking cementsknown and used as acid cements, and plug in the insulator, a water-glasssolution of 25 made from flint powder and water-glass, shrink less than35 Baum, preferably Baum, it is too strongly and have too slight anadhesiveness to be used, whilst for most purposes, where the to be ableto be used as a cement for metallic confinished product has to withstandno great temstructional parts. Bakelite also adheres badly to peratures,a water-glass solution of more than 30 metals. Asphalt cements, whichadhere well, Baum, preferably Baum, is suitable for the 30 soften attemperatures but little above roompurpose. temperature. The cementingcapacity of the last- The cement according to the invention has thementioned cements is substantially reduced by a most variedpossibilities of use, and no applicafilm of oil on the metal parts to bejoined. If tion within the scope referred to is excluded. they areglazed, ceramic constructional parts can- The new cement is speciallyadvantageous for the 35 35 not be cemented to bakelite, and if thefinished cementing of the central electrode of a sparking product whenin use is to be subject to stress due plug into the insulator in caseswhere the sparkto heat it cannot be cemented with asphalt. ing pluginsulator has a great thermal expansion.

The cement according to the invention signi- I declare that what I claimis: 40 fies a great advance over the known cements. 1. A cement forjoining ceramic and metallic 40 The advantages of the cement accordingto the materials consisting of a mixture with conceninventionarez-Greater scope of application, trated water-glass solution of 95 to99.8% of great mechanical strength and hardness, exfinely divideda'lum'ina and 0.2 to 5% of a silicoceptional adhesiveness, limited shrinkage,indefluoride. pendence of the nature of the surface of the 2. K cementfor joining ceramic and metallic 5 parts to be joined (rough or smoothmetal surmaterials consisting of a mixture with concenface, oil film,porous or glazed bodies), resistance trated water-glass solution of95-99.8% of finely to high temperatures, durability, and resistancedivided alumina and 0.2 to 5%- of magnesium to acids. These advantagesare of great imporsilicofluoride. tance, both separately andcollectively. 3. A cement for joining ceramic and metallic In thepreparation of the cement according to materials consisting of a mixturewith concenthe invention finely round alumina, preferably tratedwater-glass solution of 95-99.8% of cocorundum powder, is mix' ed withsilicofiuorides, rundum powder, and 0.25% of magnesium silicop ra y manesium sllicofluoride, namely fluoride, -99.8% by weigmpf corunHumpowder. and 4. A cement as claimed in claim 1 in which the 55concentration of the water-glass solution is varied so as to obtain thequality of cement best suited for the purpose of use.

5. A cement for Joining the central electrode of a sparking plug to theinsulator consisting of a solution of water-glass of less than 35 Baummixed with finely divided alumina and a silicofluoride.

6. A cement for joining the central electrode of a sparking plug to theinsulator consisting of a solution of water-glass of 30 Baum mixed with95-99.8% of corundum powder and 0.2-5% of magnesium silicofluoride.

ARTUR MfiHRLE.

